Use appropriate rustfmt --format ... param

This fixes the issue with c-string literals which require edition 2021. Now the edition is automatically computed if not specified.

bindgen/lib.rs

@@ -206,7 +206,7 @@ impl std::fmt::Display for Formatter {
             Self::Prettyplease => "prettyplease",
         };
 
-        s.fmt(f)
+        std::fmt::Display::fmt(&s, f)
     }
 }
 
@@ -997,6 +997,9 @@ impl Bindings {
             cmd.args(["--config-path", path]);
         }
 
+        let edition = self.options.rust_edition.unwrap_or_else(|| self.options.rust_target.latest_edition());
+        cmd.args(["--edition", &format!("{edition}")]);
+
         let mut child = cmd.spawn()?;
         let mut child_stdin = child.stdin.take().unwrap();
         let mut child_stdout = child.stdout.take().unwrap();